And probably let all the pretty girls in, no matter their age. Or did.
It is no longer a private residence, and Hefner doesn't even own it. He rents part of it from Playboy Enterprises.
Fine, but the stuff being complained about happened in the 1960s and 1970s. In any case, ownership by a corporation does not imply that age must be checked, to my knowledge. Many churches are incorporated for example, but checking the age of churchgoers on entry to a church seems as if it would be unusual. If you think age should be checked, you need to state clearly the legal reason why. For example, is the establishment a licensed bar in which alcohol is served? just that sex goes on somewhere in a privately owned or rented residence, or that a building in which sex sometimes occurs is owned by a corporation (eg hotel owned by Holiday Inn) does not seem legally sufficient to mandate an age check by guards at property perimeters.